crystal oscillator mohammad alsharafi 230 14 / 4 / 2014
TRANSCRIPT
Crystal oscillator
Mohammad Alsharafi 230
14 / 4 / 2014
WELCOME
Sinusoidal Oscillators
Electronics circuits
Transistor AMP OP AMP Timers
Sinusoidal oscillator
Crystal oscillator
Introduction
What is this device ?
Function signal generator
Why we use it in the lap?to give us a wave that we can adjust its frequency
and shape
Why we use the oscillator?to give us a wave that we can adjust its frequency
and shapeWhat is the different between
them ?
What is the different between function generator & oscillator circuit?
Discuss about the answer as partner for 5 min.
Partner work
Stability effects
• Temperature :
Rising of Temperature will change the frequency (f) and the gain (A).
To avoid this issue we should use a heat sink.
Oscillator stability
• Voltage source :
The value of voltage source is not stable by time, so the frequency will change.
By using a voltage regulator the voltage will not change, and so is
frequency.
Oscillator stability
• The load:
When we change the load the frequency will change.
To solve this problem we should put a buffer between the oscillator and the load .
Oscillator stability
• The quality factor (Q) :
• To have an accurate oscillator, the Q should be between 104 and 106.
• To have this number of Q, the impedance of the capacitor and inductor should be very small, and that is impassible.
To avoid this problem we should connect a crystal between the output and noninverter input of the oscillator
circuit.
Crystals
Topaz
Sucrose
Quartz
Berlinite
TourmalineWhat is special about these crystals?
Piezoelectric effect
• piezoelectricity means voltage resulting from pressure, or vibration resulting from voltage.
• There are thousands of application stand on this effect (such as cigarette lighter) .
video
Exercise 1
• Why we use a crystal in the oscillator circuit?
To have an accurate oscillator.
• What is special about some crystals we use them in electronics ?
The piezoelectric effect .
Part 1
Exercise
• What is piezoelectric effect ?
voltage resulting from pressure, and vibration resulting from voltage.
Exercise
• We use voltage regulator in the oscillator circuit to ……………….. .
D. Avoid Changing in voltage source.
Part 2
B. Avoid The heat.C. Avoid Changing in the load.
A. Have an accurate oscillator.
Exercise
• What is the best value of the quality factor that will makes an accurate oscillator.
D. 107
B. 103
C. 104
A. 105
Exercise
• The man on the video talked about the error of the crystal oscillator, so that error is……. .
D. Nothing correct. (what is the answer?)
B. One minute per two years.C. 3 minutes per 3 years.
A. One minute per a month.
Crystal Oscillator
Topaz
Sucrose
Quartz
Berlinite
Tourmaline
Quartz• Quartz is the second most abundant mineral in
the Earth's continental crust.
• It is made up of SiO4 silicon–oxygen tetrahedra.
• There are many kind of quartz.
Quartz oscillator
• Quartz oscillator is as like as any other electronics component.• It has symbol and different values.• Its values start from a few kilo Hertz to hundreds of hertz.
symbol equivalent circuit
Exercise 2
Group of 3
Each group will do the task In the whiteboard for 5 min
• Draw the symbol and the equivalent circuits of the quartz oscillator.
Crystal oscillator
Mohammad Alsharafi 230
14 / 4 / 2014
THANK
YOU